Saw chain cutters with thin cutting portion and thick base



Aug. 4, 1959 FIG. 2.

R. R. CARLTON SAW CHAIN CUTTERS WITH THIN CUTTING PORTION AND THICK BASE Filed April 29, 1957 34 I E; *22 FlG.3 :2 H

. INVENTOR. RAYMOND R. CARLTON BY "w ATTORNEYS United States Patent SAW CHAIN CUITERS WITH THIN CUTTING PORTION AND THICK BASE Raymond R. Carlton, Portland, Oreg., assignor to Omark Industries, Inc., a corporation of Oregon Application April 29, 1957, Serial No. 655,828 3 Claims. (Cl. 143-135) The present invention relates to .chain saws and more particularly to a new and improved construction of a saw chainfor chain saws.

Saw chains of the type with which the invention is concerned comprise a plurality of center links which are pivotally connected together by oppositely postioned side links. The center links of the chain are each provided with a root portion which slides within a slot formed in the edge of a flat metal saw or guide bar which protrudes from the motor of a saw and about which bar the saw chain is trained. The side links of the chains silde upon the opposite rails of the 'saw bar which rails define the slot receiving the roots of the center links, certain of the links, certain of the side links are formed with cutting elements for cutting a kerf in wood or other material being sawed.

Heretofore, it has been the practice to form the side links of the chain of metal plate of substantially uniform thickness. Because the cutter elements have to slice through the wood, the side links have been made as thin as possible to minimize the resistance to the passage of the cutters through the wood. However, dirt and other abrasive material frequently gets between the side links and the rails of the guide bar. This results in rapid wear of the thin edegs of the links which are in engagement with the rails of the guide bar. Accordingly, the wearing away of the side links against the guide bar has frequently destroyed the usefulness of the links and the chain long prior to the time the cutters themselves are worn beyond the point of resharpening.

It is, therefore, an object of the invention to provide a saw chain construction that will prolong the life of the chain.

More particularly, it is an object of the invention to provide a saw chain side link construction in which the side links have greater resistance to wear along the edges of such links which engage the guide bar of a chain saw and in which the cutting elements carried by certain of said side links have greater cutting efliciency.

Further objects and advantages of the invention will become more apparent hereinafter.

In accordance with the illustrated embodiment of the invention, a saw chain is provided with side links wherein the portion thereof adjacent the edge in engagement with the guide bar of a chain saw is of greater width than the remaining part of the link whereby a greater mass of material is presented to wear away, thus prolonging the life of the side links.

For a more detailed description of the invention, reference is made to the following specifications and the accompanying drawings.

In the drawings, Fig. l is a perspective view of a fragmentary length of chain made in accordance with the invention in position on a guide bar therefor;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1; and

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Fig. 3 is a view similar to Fig. 2 of a modified form of the invention.

Referring to Figs. 1 and 2, the illustrated saw chain comprises a plurality of longitudinally spaced apart center links 10 having sprocket engaging root portions 11 formed thereon and which are adapted to be engaged by a driving sprocket (not shown) of the chain saw. The links 10 are pivotally connected together by means of oppositely disposed side links or side plates 12 and 13 and rivets 14 forming pivot pins for the various links and extending through suitable rivet apertures in the side plates 12 and 13. Side links 12 are simple connector links and are all identical to each other. The side links 13 are each formed with a hook shaped tooth on its upperends and each is provided with a depth gauge 16 ahead of its tooth. Alternate side links 13 are allochiral.

The chain is shown as being supported upon a chain saw guide bar 18 formed on its periphery with a pair of opposite rails 22 upon which the side links 12 and 13 are supported and which define a slot or groove 23 for receiving the center link root portions 11.

The side links 13 form the cutting teeth of the chain and in the embodiment illustrated in Figs. 1 and 2, they are formed from a tapered metal plate to define a body element 24 and a cutter element 26 including a reversely bent shank portion 28 and a toe portion 30 extending from the shank portion in a direction transversely of the body portion 24. The plate is of progressively increasing thickness from the end of the toe portion 30 through the body element 24, whereby the cutter element 26 is relatively thin so as to slice through wood with a minmum of resistance whereas the lower edge of the body element which slides upon the guide bar is of greater thickness. Each tooth, therefore, engages the guide bar over a relatively large area so that the pressure of engagement for a given area is less than it would be if the edge portion of the tooth were of smaller area. Since the pressure of engagement is less, the rate at which the edge portion of the tooth wears away will be lessened, thereby prolonging the life of the tooth. As indicated in Fig. 2, the side links 12 are made of similarly tapered stock but as shown in Pig. 1, are not formed with a cutter element and serve merely as connecting links of the chain.

In the embodiment of the invention illustrated in Fig. 3, the cutting teeth 13 are formed with a toe portion 30 and reversely bent shank portion 28' as in the previously described embodiment, but in this case the tooth is formed of stock which is of uniform thickness throughout except for the portion 34 immediately adjacent the edge in engagement with the guide bar, and which portion is upset or otherwise formed so as to be of greater thickness. Thus the surface area of the tooth in engagement with the saw bar is increased with a resulting lesser rate of wear of the tooth. The connector side links 12' are similarly formed of stock having an upset or otherwise thickened portion 34 adjacent the edge portion which slides upon a rail 22 of the guide bar 18.

Having illustrated and described preferred embodiments of the invention, it should be apparent to those skilled in the art that the invention permits of modification in arrangement and detail. I claim as my invention all such modifications as come within the true spirit and scope of the appended claims.

I claim:

1. A saw chain tooth formed of a metal plate and comprising a body element having rivet apertures therein and having an integral cutter element projecting from one edge of said body element and including a reversely bent shank portion extending outwardly from the outer surface of said body element and a toe portion extending laterally of said body element from said shank portion inwardly 3 past the inner surface of said body element, the opposite edge of said body element providing a bearing surface for sliding on a guide bar, said body element having a portion of increased thickness extending from said opposite edge toward said rivet aperture'at least a major portion of the distance between said opposite, edge and said rivet apertures, said inner surface-being flat adjacent'said opposite edge and said bearing'surface being' flat throughout its areaand extending to and intersecting said inner surface. 7 2. A saw chain tooth formed of a metal plate and comprising a body element having rivet apertures therein and having an integral cutter element projecting from one edge of said body element and including a reversely bent shank portion extending outwardly from the outer surface of said body element and a toe portionextending laterally of said body element from said shankportion inwardly past the inner surface of said' body element, the opposite edge of said body element providing a bearing surface for sliding. on a guide bar, said body element having a portion of increased thickness extending from saidopposite edge toward said rivet aperture 2. major portion of the distance between said opposite edge and said rivet apertures, said portion of increased thickness terminating at aposition spaced toward said opposite edge from said rivet apertures and the remainder of said body element being of substan- 25 tially uniform thickness, said inner surface being flat adjacent said opposite edge and said bearing surface being flat throughout its area and extending to and intersecting said inner surface.

3. A saw chain tooth formed of a metal plate and comprising a body element having rivet apertures therein and having an integral cutter element projecting from one edge of said body element and including a reversely bent shank portion extending outwardly from the outer surface of said body element and a toe portion extending laterally of said body element from said shank portion inwardly past the inner surface of said body element, the opposite edge of said body element providing a bearing surface said opposite edge, said inner surface being fiat adjacent.

for sliding on a guide bar, said body element having a portion of increased thicknessextending from said opposite edge toward said rivet apertures at least a major portion of the distance between said opposite edge and said rivet apertures, said body portion being tapered to increase in thickness from said one edge to said opposite edge and said portion of increased thickness constituting the resulting thicker portion of said body portion adjacent said opposite edge and said bearing surface being'flatthroughoutits area and extending to and intersecting saidinner surface.

References Cited in the file of this patent UNITED STATES PATENTS 2 ,508,784 Cox May 23, 1950 FOREIGN PATENTS 809,711 Germany Aug. 2, 1951 891,921 Germany Oct. 1,1953 

